WASHINGTON — Sen. Susan Collins said Wednesday that she opposes President Barack Obama’s choice of former Sen. Chuck Hagel to take over the Defense Department. However, Collins said she wouldn’t join a filibuster to block a final vote on his nomination.

In a lengthy statement released by her office, Collins said Hagel’s views on addressing threats of Islamic extremism and violence in Israel were “unsettling” to her.

“For example, with regard to Hezbollah, Senator Hagel was unwilling to ask the European Union to designate Hezbollah as a terrorist organization in 2006,” Collins said in the statement. “While 88 other senators, including then-Senators Obama and [Hillary] Clinton, supported this reasonable request, Senator Hagel did not.”

She praised Hagel’s military service, but was critical of his stance on North Korea and al-Qaida.

“I believe a vote in favor of Senator Hagel would send the wrong signal to our military, the American people, and to the world about America’s resolve regarding the most important national security challenges of our era,” she said.

All the Republicans on the Senate Armed Services Committee have opposed Hagel’s nomination. Sen. David Vitter of Louisiana didn’t cast a vote, however, saying he thought Hagel’s nomination was being rushed through the Senate.

The Armed Services vote followed a contentious confirmation hearing in late January during which Republicans questioned Hagel’s judgment on war strategy and put him on the defensive for past statements and Senate votes.

In one of the most heated exchanges, Sen. John McCain aggressively questioned Hagel, interrupting him and talking over him at times. He voiced frustration at the former Republican senator’s failure to say plainly whether he was right or wrong to oppose the 2007 “surge” of U.S. troops in Iraq.

“Your refusal to answer whether you were right or wrong about it is going to have an impact on my judgment as to whether to vote for your confirmation or not,” McCain said.

Sen. Lindsey Graham of South Carolina laid into Hagel for once accusing a “Jewish lobby” of intimidating people in Washington, comments Hagel repeatedly said he regretted. Asked whether he could name one lawmaker who had been intimidated, Hagel said he could not. It was one of the many times he appeared uncomfortable.

“I can’t think of a more provocative thing to say about the relationship between the United States and Israel and the Senate or the Congress than what you said,” Graham said.

While Hagel will enjoy widespread Democratic support, only two Republicans — Sens. Thad Cochran of Mississippi and Mike Johanns of Nebraska — have said they will support for him.

It remains unclear whether Republican senators will try to filibuster the nomination. Regarding this possibility, Collins said Wednesday: “Should this nomination, which causes me such great concern, be filibustered? As a general rule, I believe a president has the right to choose the members of his cabinet, and only in extraordinary circumstances should such a nomination be filibustered. I oppose Senator Hagel’s nomination, but I cannot join in a filibuster to block each senator’s right to vote for or against him.”

Late Wednesday, Senate Democrats filed a motion to end debate on the nomination, setting up a showdown vote by Friday.

Democrats are expected to muster the 60 votes needed in the 100-member chamber to clear a Republican procedural roadblock, clearing the way for a vote on his confirmation.

Once the roadblock is cleared, Hagel is expected to win the simple majority of Senate votes he needs to be confirmed.